MOSFET for PWM LED Driver

Thread Starter

newaisa

Joined Dec 6, 2011
12
The LEDs are rated for 5V, does that mean they have built-in resistors? Just to make sure.
I didn't draw it in the other post because I was assuming they have them...
Yes, you are right. Every single pixel is waterproof has resistor built in.

Btw, now that you mentioned heatsick. I have thought of that as well. Can you suggest on that?I am not too sure which type to go.
 

SgtWookie

Joined Jul 17, 2007
22,220
Now back to my previous question. Do you think my idea of driving my PMOS this way will work?

Did you see praondevou's reply #15 where he posted this schematic?


Your schematic does not look like his PNP schematic.

By the way, you have the drain and source terminals reversed. Notice the FET body diode? It would allow current to pass through the MOSFET whether it was on or not.
 

Wendy

Joined Mar 24, 2008
22,181
The LEDs are rated for 5V, does that mean they have built-in resistors? Just to make sure.
I didn't draw it in the other post because I was assuming they have them...

If they don't you will need them.

6A for this MOSFET will be ok. Put them on a heatsink though.
Leds are never voltage devices. When you see a LED on eBay saying it is for 12V the resistor is included. It would be the same for 5V devices, but it is a mistake to assume anything. Verify!
 

Thread Starter

newaisa

Joined Dec 6, 2011
12
Did you see praondevou's reply #15 where he posted this schematic?


Your schematic does not look like his PNP schematic.

By the way, you have the drain and source terminals reversed. Notice the FET body diode? It would allow current to pass through the MOSFET whether it was on or not.
Yup noticed that, it was my drawing mistake :p

Leds are never voltage devices. When you see a LED on eBay saying it is for 12V the resistor is included. It would be the same for 5V devices, but it is a mistake to assume anything. Verify!
Noted. Those LEDs have been running for years with 5V power supply. So I am quite sure the resistor built in is right to limit the current that gets to LED.

Btw, still having trouble looking for a heatsink for my mosfet~any suggestion? @_@
 
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